Method and apparatus for sorting by size

ABSTRACT

Articles, such as apples, to be sorted by size, float in water along a main channel. Depending upon the depths to which the apples penetrate below the surface of the water, the apples may be diverted into one of a plurality of side channels by endless belts positioned at respectively different depths beneath the surface of the water.

This invention relates to a method and apparatus for sorting articles bysize in liquid.

There is a need in the fruit industry for a sorter of simpleconstruction which will reliably sort apples according to size withoutcausing excessive damage. In USSR patent No. 776593 there is disclosed asorter in which articles to be sorted are dropped into a moving body ofwater. The water at different depths moves in laminar flows at differentspeeds, the speeds of the flows increasing with depth.

Articles of greater density descend to greater depths and are sweptfurther along before returning to the surface. Barriers lying in thesurface trap the articles as they return to the surface, and separatethem according to their density. Satisfactory sorting depends on theability to provide laminar flows of water travelling at accuratelydefined speeds.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided amethod of sorting articles by size in liquid, characterised in thatfloating articles are sorted according to the depths to which theypenetrate below the surface of the liquid.

According to another aspect of the invention there is provided sortingapparatus including a container for liquid, means for causing articlesto travel through the container, and at least one barrier disposedwithin the container, characterised in that the or each barrier has anupper surface portion positioned so as to lie at a predetermined depthbeneath the surface of liquid in the container so as to make contactwith articles floating in the liquid and penetrating at least to thatdepth.

When apples are to be sorted it will be convenient to use water as theliquid. It may, however, be preferable to sort some other types of fruitin brine, while other liquids may be used for other articles.

Preferably the apparatus includes a number of barriers, each including ahorizontally extending moving belt for diverting articles from a mainchannel into a respective branch channel. Alternatively, there may be asingle barrier, which may take the form of a wide band travelling in thedirection transversely of the main channel. The upper surface of theupper run of the band decreases in depth in the downstream direction sothat articles come to rest upon it in positions determined by theirsize.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings,

FIG. 1 is a perspective view of the preferred apparatus, in which theend of the apparatus nearer to the observer is the upstream end and thatfurthest from the observer the downstream end,

FIG. 2 is a vertical section taken longitudinally of the main channel,showing the entrance to one branch channel and the exit elevatorconveyor.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings, a sorter particularly for apples includes acontainer 1 for water. The container may be in the form of a metal bathhaving parallel side walls 2 and 3, a downstream end wall 4 and anupstream oblique wall 5, shown partially broken away. The wall 5 is atan angle of about 150° to wall 3. A narrow entry section is formedbetween an end portion of side wall 2, a wall 6 adjoining wall 5, and anupstream end wall 7. Disposed within the container is a series of spacedapart elongate casings 8 which extend parallel to-the wall 5.

The casings may be formed by pressing up the bottom of the bath or maybe separate components fixed in place. The casings 8 terminate at theirends nearer to the wall 2 in walls 9. In line with the walls 9, andspaced from the casing depicted furthest from the observer is a wall 14.The walls 9 and walls 6 and 14 define with the wall 2 a main channel A.The walls 9 define with one another and with the wall 6 and wall 14 sixoutlets 11 from the main channel. The outlets 11 are less deep than thechannel A, being provided with thresholds 12 extending to the base ofchannel A. Interposed between the walls 3 and 14, and extending parallelthereto are five walls 13, each of which at its upstream end forms thatend wall of a respective casing remote from its wall 9. The walls 13define with one another and with the walls 3 and 14 a group of sixbranch channels B extending parallel to the main channel A, andcommunicating therewith by way of the outlets 11. In the case of thefive channels nearer the wall 3, the branch channels include obliquelyextending channel portions C, each of which is defined between thelonger sides of two adjacent casings or (in the case of the secondarychannel nearest to the observer) between the wall 5 and the adjacentcasing. The bases of channel portions C are below the upper edges ofthresholds 12.

A low wall 10 extends between the walls 2 and 3 at right angles theretoin order to define with the wall 4 a sump D. In the case of that part ofthe bath which defines the channel portions B and C, the bottom of thebath upstream of wall 10 is horizontal and adjoins the upper edge ofthat wall. The bottom of the part of the bath which defines channel Aupstream of wall 10 is lower and adjoins the base of that wall.

Channel A is provided with an adjustable false floor 16 which isinclined upwards in the downstream direction and which, at itsdownstream end terminates in the region of the upper edge of wall 10.The wall 4 defines the downstream end of the sump D and serves as a weirover which water may flow into a trough E defined between wall 4 and afurther wall 15.

An entry conveyor 20 descends into the entry section of the bath betweenthe walls 2 and 6, and overlies the upstream end wall 7 of this section.An exit elevator conveyor 22 extends the full width of the bath at itsdownstream end and descends into the space formed by the sump D. Bothconveyors are of such construction as to allow the free passage of waterthrough them, and may be of slatted or roller construction.

The walls 13 and 14 are cut-away on their undersides as at 23 so as tooverlie the conveyor 22. Fences, not shown, may serve to continue thewalls 13 and 14 along all or some of the length of the conveyor, orother means may be provided for keeping sorted apples separate.

Mounted on respective upper surfaces of the casings 8 and on theupstream end of the wall 14 are six electric motors 24, each motordriving a pulley wheel. Circuitry for energising the motors 24 and pumpsreferred to hereinafter is also provided. A pair of rotationally coupledpulleys 25 is supported on a shaft mounted within each branch channelbelow the respective motor, just within the channel at its upstream end.A return pulley 26 is supported on the wall 2. The shafts of pulleys 25and 26 are adjustable in the vertical direction, suitable guides carriedby the casings 8, wall 14 and wall 2 and releasable fixing means, beingprovided for this purpose. A drive belt 21 is trained over the motorpulley and the pulley of the pulley pair 25 nearer the casing or wall14, as the case may be. A guide belt 27 is trained over the returnpulley 26 and the other pulley of the pulley pair 25. When the motorsare energised, the upper runs of belt 27 are caused to move in thedirection indicated by the arrows. Suitable deflectors (not shown) maybe provided to prevent apples to be sorted fouling the guides for thepulleys.

In use, the bath is filled with water to the level W, defined by theheight of wall 4. Water is constantly supplied through an inlet duct 30in the upstream end wall 7 and drawn off through outlets 31 in the sumpD. The rate at which water enters the bath is somewhat greater than therate at which it is removed through outlets 31 to ensure that the wall 4acting as a weir maintains the desired level. The water passing over theweir is collected in trough E and drawn off through outlets 34. A flowof water is therefore established within the bath, along the length ofeach of the channels. The end wall 9 of each casing facing the wall 2 isprovided with jets 32. Jets 33 in each threshold 12 directed away fromthe main channel assist in establishing flow into each branch channel inthe region of the entrance. The provision of the false floor 16 ensuresthat flow along the main channel is maintained at approximately constantspeed throughout its length, despite diversion of a proportion of theflows into the branch channels. Separate pumps, not shown, recirculatethe water escaping through outlets 31 and 34, supplying the waterthrough a system of pipes to the inlet 30 and to jets 32 and 33,respectively.

Apples O or other articles to be sorted placed onto the entry conveyor20 are deposited in the water in the entry section of the main channeland float along the main channel adjacent to wall 2. The pulleys 25 and26 have previously been adjusted in height relative to the water levelsuch that the upper run of each belt 27 is horizontal and at such adistance below the water surface that it will make contact with applesfloating in the water and penetrating to a predetermined depth. Thedepth of the upper run of each belt after the first is less than that ofthe preceding one in the upstream direction. The largest applesencounter the most upstream belt, the next largest encounter the nextadjacent belt, and so on, while apples which are smaller than thepredetermined minimum size pass over all of the belts and continue alongthe main channel.

The water issuing from the jets 32 causes the apples to float adjacentwall 2, so that they will only enter the desired outlet 11 to a branchchannel under propulsion from the associated belt. The water emergingfrom the jets 33 helps ensure that once apples have been propelled intoan outlet by the associated belt they will continue along the branchchannel reliably, rather than accumulate in the entrance. The continuousflow of water along the channels brings the apples onto the exitelevator conveyor, which lifts them out of the water and conveys them inseven lines through stations at which they are rinsed, dried in an aircurrent and then removed and packed.

Modifications may be made to the illustrated arrangement. Thus, forexample, the upper surface of each of the belts 27 when viewed in crosssection may be linear and disposed horizontally, or at an angle to thehorizontal, or the upper surface may be curvilinear. The belt may be ofone piece construction, or of composite construction so as to facilitatethe provision of a surface with a sufficient coefficient of friction.Provided a sufficient rake is provided, stationary barriers may be usedin place of the belts 27. Alternatively, the barriers may includerotating rollers, vibrating bristles or fingers. There may be two ormore barriers at the same depth. All of the barriers at the same depthmay feed into one and the same branch channel or into respective branchchannels.

In a further modification, a single endless belt may be employed in theform of a wide band, the upper run of which decreases in depth in thedownstream direction so that the articles land on it at differentdistances from its upstream edge, depending upon the sizes of thearticles. The band travels in a direction at right angles to the flowdirection. The band may be provided with cup-shaped depressions or withribs so as to convey the articles reliably out of the flow stream.Instead of using pumps to produce circulation of liquid, paddles may beused to circulate water around a closed loop.

The widths of the channels may be slightly greater than the diameters ofthe articles to be sorted so as to ensure that the articles arrive onthe elevator 22 from each channel in single file.

Although the articles are shown to travel through the tank under theeffect produced by a moving current of liquid, it falls within the scopeof the invention for the liquid to be still and for other means to beprovided for propelling the articles. Such means may, for example, takethe form of moving fingers contacting the articles, or jets of air. Itwill also be appreciated that the invention may be applied to articlesfloating in a naturally flowing body of water, so that no container ortank as such is provided in order to retain the water. Although it ispreferred to fabricate the bath from metal, it may be moulded from fibreglass material or from plastics, or constructed from wood or othermaterials and have a water impervious lining.

The wall 4 which serves as a weir may be adjustable in height so as toallow the water level to be varied and one or more additional weirs maybe provided in wall 2 so as to reduce the effect of turbulence in theflow along channel A. The liquid escaping from the additional weirs maybe led to trough E.

I claim:
 1. Apparatus for sorting buoyant articles floating on thesurface of a liquid, comprising:a container for the liquid, saidcontainer having a bottom, a first substantially straight vertical sidewall, a plurality of second substantially straight vertical side wallsobliquely disposed with respect to the first side wall and each of saidsecond side walls having a first end spaced a substantially uniformdistance from said first wall so as to define therewith an open-toppedmain channel extending horizontally in a longitudinal direction of thefirst vertical side wall, and coextensive therewith, said containerhaving an upstream end at a first end of said first sidewall and adownstream end at a second end of said first sidewall; said second sidewalls extending substantially parallel to each other and spaced apartfrom one another to define therebetween a plurality of outlets from themain channel; a plurality of third vertical walls each attached to asecond end of a corresponding second sidewall, said third vertical wallsand said second vertical sidewalls defining a plurality of open-toppedbranch channels, each branch channel extending horizontally and openingthrough a respective one of said outlets into the main channel; saidfurther walls defining portions of the branch channels which extendhorizontally parallel to the main channel; a plurality of relativelynarrow endless belts, each said belt having a horizontal upper runextending across the main channel at a position adjacent the downstreamedge of a respective outlet; means for causing said belts to circulatesuch that the upper run of each belt travels in the direction away fromsaid first wall towards a corresponding said outlet; means for supplyingand removing liquid from the container and establishing a predeterminedliquid level in each channel of the container above the upper runs ofsaid belts, all of said levels being in substantially the same plane;means for adjusting the height of the upper runs of said endless beltsrelative to the bottom of the container, thereby to position each beltupper run at a predetermined depth beneath the predetermined liquidlevel the depths of said upper runs below the predetermined liquid leveldecreasing in the downstream direction; means for causing liquid to flowfrom the upstream end of said main channel to the downstream end of saidmain channel, and from each outlet thereof along each of said branchchannels to a downstream end of each of said branch channels; means forintroducing articles to be sorted into the upstream end of the mainchannel; means for removing sorted articles from the downstream end ofsaid main channel and from each of said branch channels;
 2. The sortingapparatus of claim 1, wherein each said endless belt is drivinglyconnected to a respective motor.
 3. The sorting apparatus of claim 2,further including jets disposed in the second side walls for dischargingliquid into said main channel to cause articles floating therein to bedisplaced from the second wall.
 4. The sorting apparatus of claim 3,further including jets associated with each outlet and directed into abranch channel and away from said main channel.
 5. The sorting apparatusof claim 4, wherein said means for introducing and removing articleseach comprise conveyor belts which extend to positions below the liquidlevel.
 6. A method of sorting different sizes of buoyant articles bysize wherein the articles to be sorted float in the surface of a liquid,the larger articles having portions which are disposed at levels belowthe surface of the liquid deeper than portions of the smaller articles,all of the articles being made to float in the liquid surface along amain channel having a feed end and a discharge end spaced therefrom,said method including the steps of:providing in said main channel firstand second distinct, individually vertically adjustable, endless beltconveyors, each belt conveyor spaced from the other and oriented toconvey a given sized article out of said main channel, said first beltconveyor located upstream in said main channel and being closer to saidfeed end of the main channel than said second belt conveyor, said firstbelt conveyor being located at a first predetermined depth in said mainchannel that is deeper than a second predetermined depth at which saidsecond belt conveyor is located; feeding the buoyant articles ofdifferent sizes into the main channel; sorting the articles of a largersize by contacting the larger size articles against said upstream firstbelt conveyor positioned beneath the surface of the liquid at said firstpredetermined depth; deflecting the larger size articles by the firstbelt conveyor to one side of the main channel and into a first secondarychannel while still floating in the liquid surface; floating thearticles of a medium size and smaller size that do not encounter thefirst belt conveyor over the first belt conveyor to continue along themain channel; sorting the articles of a said medium size by contactingthe medium size articles against said second belt conveyor positionedbeneath the surface of the liquid at said second predetermined depthwhich is less than said first predetermined depth; deflecting thearticles of said medium size articles by said belt conveyor into asecond secondary channel while still floating in the liquid surface; andfloating the smaller articles which do not encounter the second conveyorover the second conveyor to continue along the main channel.
 7. Themethod of claim 6, wherein said first and second belt conveyors movehorizontally across the main channel and carry with them those articleswhich encounter the respective first and second belt conveyors.
 8. Themethod of claim 6, further comprising the step of directing a jet ofliquid from an inlet of each of said secondary channels into thesecondary channels to thereby assist in directing the articles into thesecondary channels.